Air mask



FIG. 1 is a front perspective view of an air mask, showing our new design, the broken line showing of the headgear and supply conduit is for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a cross-sectional view thereof, taken along line 8--8 of FIG. 2. 

The ornamental design for an air mask, as shown and described. 